Intramedullary nails are commonly used as bone fixation devices for osteosynthesis purposes. Often these intramedullary nails feature locking screws inserted transversely through the intramedullary nail for either stabilizing the intramedullary nail in the bone or for fixation of individual bone fragments. These intramedullary nails may permit multiple locking screws to be inserted therethrough at different angles relative to one another. The locking screws are often secured in the intramedullary nail via a plastic bushing or ring preventing the screw from migrating out of the intramedullary nail due to micro-motion or other loads. To secure these screws in the intramedullary nail, an interference fit and a forced tapping of the screw into the bushing is generally applied. Other fixation features include metal interfaces that may be mechanically deformed and/or permit forced tapping in metal. These bushings should be formed of a material that is biocompatible. However, there is limited availability of such a material. One such available plastic material is Ultra High Molecular Weight Poly-Ethylene (UHMWPE), which is a material that has been approved worldwide for implantation. Although the biocompatibility of this material is ideal, the material is difficult to process with required accuracy using conventional processing and molding techniques.
An example of a locking intramedullary nail including transverse locking holes and an insert for securing the locking screws in these locking holes is known from EP Patent No. B 0 306 709 DAUERER. This known intramedullary nail comprises a proximal and a distal insert with transverse bores having a diameter smaller than the outer diameter of the locking screws so as to secure the locking screws in the locking holes of the intramedullary nail. The insert is slidably inserted into the central cavity of the intramedullary nail. This known intramedullary nail, however, does not comprise an attachment structure at the proximal end to fix an insertion instrument to the nail.
One problem associated with the above described intramedullary nails involves the attachment mechanism for an insertion handle or aiming device which is usually arranged at the proximal end of commonly used intramedullary nails is that the insert must have a small outer diameter in order to be introduced through a central opening of the attachment mechanism.
Thus, there remains a need for an improved intramedullary nail for a rigid fixation between the nail and the bone including an attachment mechanism for a surgical instrument and an insert, which permits the locking screws to be firmly secured in the locking holes of the intramedullary nail.